TUBE™ Coax Line Isolator Choke, 1-161 MHz, 1.5KW, SO-239 In/Out
1.5 KW PEP, 50 ohm In/Out, 1-161 MHz, Feed Line Choke/Line Isolator
TUBE feed line chokes are used to suppress common mode current carried on the outside of the coax braid which is often responsible for receiver noise and RFI in the receiver/transmitter. These chokes are very useful for suppressing RFI common mode current at the antenna feed point, at 1/4 wavelength intervals along the coax feed line and also at the entrance to the radio station. They are available with various input and output connectors so as to conveniently connect to standard output connectors already installed on your feed line.
Palomar Engineers TUBE feed line chokes are designed to have 2-5 times more choking impedance over a broader frequency range than competitor units in similar packaging. Each choke has the choking impedance and effective frequency range on the product label so you can choose the product best suited for your application.
Note: Color may be white or black depending on on inventory at time of order.
This line isolator feed line choke is a convenient choke for placement in a coax line with PL-259 male connectors. The choke’s female SO-239 connectors allow easy plug in and the excellent choking characteristics suppress RFI common mode currents effectively. For best results install one choke at the antenna feed point to keep RF on the antenna and off the coax braid and another choke at the radio station entrance to reduce the noise picked up by the coax braid between the antenna feed point and the station entrance. Typical impedance choking is 500 – 6000 ohms (over 3000 ohms from 7-61 MHz). Most experts agree that the choking impedance of a feed line choke should be at least 10 times its characteristic impedance (e.g. 500 ohms minimum for a 50 ohm coax impedance). This choke provides excellent common mode current suppression for 14-54 MHz multi-band amateur beams , 4 and 6 meter antennas, as well as commercial and amateur antenna systems from 30-160 MHz.
This choke is available with a SO-239 input/output and ground lug (optional) for attachment to a ground rod. Use an isolator every 1/2 wavelength for the antenna operating frequency (include velocity factor in calculation). Use the ground lug option for long coax antenna feed lines (over 1/2 wavelength at the operating frequency of any antenna system in the near field of the coax).
Typical choking impedance verses 1-61 MHz frequency range is shown in the graph:
Note this choke is useful out to at least 161 MHz as shown in the graph out to 161 MHz.